The purpose of this investigation is to quantify the various dc potentials that can be recorded from the cochlea in response to sound stimulation. These dc potentials are an aggregate response, composed of several components, all of which presumably originate in different sources and have their genesis in different mechanisms within the cochlea. Our purpose is to identify these sources and mechanisms, and to delineate the significance of these dc potential components in the process of hearing. We also seek to record and identify the generator potential of the cochlea, which is hypothesized to be the direct precursor of the all-or-none discharges in the auditory nerve.